In automobiles featuring an automatic transmission, a torque converter is typically positioned between the vehicle's engine and transmission. The torque converter couples the engine to the transmission and causes the transmission to rotate at a rate corresponding to the rotation rate of the engine. The torque converter also allows the engine to continue spinning even when the vehicle and, correspondingly, the transmission come to a stop. A typical torque converter includes a pump, turbine and stator. The torque converter also includes a housing which encloses the parts of the torque converter and has an impeller. The housing is fastened to an engine flywheel. The turbine is typically connected to the transmission. Fluid enclosed by the housing is circulated by rotation of the impeller and causes the turbine and, thereby, transmission, to rotate. The stator redirects fluid within the torque converter and provides for torque amplification.
A typical torque converter in a modern automobile includes the capability to selectively “lock” the turbine to the impeller, thereby, causing the turbine and impeller to rotate at the same speed. Thus, the engine and transmission rotate at the same speed. Locking the turbine to the impeller improves the efficiency of the torque converter by eliminating pumping losses in the fluid. To ensure that the locking does not cause an uncomfortable jolt in the vehicle's driveline, a typical torque converter includes a damper and a centrifugal pendulum absorber. A typical centrifugal pendulum absorber absorbs engine vibrations at a wide range of engine speeds. The mass and corresponding rotational inertia of the centrifugal pendulum absorber is used to absorb driveline vibrations.
As modern automobiles become more feature packed, smaller, and/or lighter, it is ever more desirable to reduce the size of driveline components. Often, the space in which the transmission must fit is limited. In some modern automobiles, larger transmissions with an increasing number of gear ratios are used. To compensate for this, it is desirable to reduce the size of other transmission components such as the torque converter. However, as many torque converters are already designed to be as compact as possible, it is increasingly difficult to find a way to reduce their size while still maintaining sufficient durability, performance, and acceptable costs. Simply reducing the size of the pendulum absorber assembly negatively affects its performance by reducing its rotational inertia and, thereby, its ability to absorb vibrations. This results in increased driveline harshness and noise. In current torque converters, the pendulum absorber assembly takes up a fair amount of space. To date, no manufacturer has been able to create a solution to meaningfully and cost effectively reduce its size.
What is needed therefore, is a more compact torque converter with equal or better performance, durability, and cost than existing torque converters. What is also needed is a pendulum absorber assembly that is more compact but with the same or increased rotational inertia and that still provides equal or better performance, durability, and cost than existing torque converters.